1. Field of the Invention
This invention relates to surgical apparatus, and more particularly to endoscopic electrocautery instruments such as bipolar scissors.
2. Description of Related Art
Endoscopic surgery is widely practiced throughout the world today and its acceptance is rapidly growing. Much of the popularity of endoscopic surgery can be attributed to its a less invasive, less traumatic affect upon the patient in comparison with standard open type surgery.
One type of endoscopic surgery involves placing trocar tubes into the patient through incisions and inserting endoscopic surgical tools through the trocar tubes for performing operations at a surgery site. A camera, magnifying lens, or other optical instrument is often inserted through one trocar tube, while a cutter, dissector, or other surgical instrument is inserted through the same or another trocar tube. The cutter, dissector, or other instrument is used to manipulate and/or cut tissue or organs of the patient. It may be desirable to utilize several trocar tubes at once to receive numerous surgical instruments. In this manner, a patient's organs or tissue may be, for example, grasped with one surgical instrument and simultaneously cut with another, all under the view of the surgeon via an optical instrument inserted through a trocar tube.
Various types of endoscopic surgical instruments are known in the art. Certain of these instruments may generally include an elongated, slender tube containing a push rod which is axially movable within the tube by way a handle or trigger-like actuator. An end effector is normally provided at the distal end of the tube and is coupled to the push rod so that axial movement of the push rod translates to rotational or pivotal movement of the end effector. End effectors may be, for example, scissor blades, grippers, cutting jaws, or forceps.
Modem endoscopic procedures often control a patient's bleeding in the surgical site through the use of electrocautery. Electrocautery passes cautery current to the surgery site to cauterize open blood vessels. Beyond reducing blood loss, electrocautery aids the operation by providing a clearer view of the surgical site. As used herein, the phrases cautery, electrocautery, and coagulation are interchangeable.
Several types of electrocautery instruments for use in endoscopic surgery have been described. One category of endoscopic electrocautery instruments is bipolar devices. Bipolar electrocautery instruments generally include two electrodes closely spaced for contact with organs and tissue of the patient. Typically, a bipolar electrocautery instrument includes two end effectors, one end effector acting as a first electrode, and the other end effector acting as a second electrode. The electrodes are electrically isolated from each other and include a separate current path back through to a current connector located adjacent the handle of the instrument. Thus, during contact of the bipolar instrument with an organ or tissue of the patient, current flows from the first end effector electrode, through the tissue to be cauterized, to the second end effector electrode of the bipolar instrument.
One type of bipolar electrocautery instrument used in endoscopic surgery is bipolar scissors. Bipolar scissors include first and second electrodes formed about scissor blade shaped end effectors. In operation, the end effectors cut tissue of the patient while cauterizing severed blood vessels at the surgery site.
Various problems have been encountered in the design, manufacture, and use of endoscopic electrocautery instruments. These problems include maximizing the current flow to the intended cauterizing area, maintaining a constant current supply to the end effectors, and manufacturing a reliable instrument for a reduced manufacturing cost and long life.